Whittlesea Crime Investigation Unit detectives are investigating a suspicious grass fire in Epping on January 15.
Emergency services were called to the fire on Genesis Drive just after 9pm.
Investigators have been told a man was seen walking his dog before walking to the middle of a vacant block and setting the long grass on fire.
He then left the scene on foot, heading south towards Revelation Road.
The man is perceived to be Caucasian, about 180 centimetres tall with a medium build, wearing dark-coloured shorts and a black and white t-shirt.
He was walking a small dark-coloured dog with white markings on its chest.
Investigators have released CCTV of a man they believe can assist with their enquiries.
Detectives are also investigating a previous fire at the same location about 7pm on January 11.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or make a report online at crimestoppersvic.com.au.
